SMAD protein complex heteromeric SMAD protein complex 2009-11-16T02:44:37Z GO:0071145 GO:0071144 GO:0071146 SMAD3-SMAD4 protein complex SMAD1-SMAD4 protein complex SMAD2-SMAD3-SMAD4 protein complex SMAD2-SMAD4 protein complex cellular_component A protein complex composed of SMAD family proteins, a transcription factor complex which binds to the promoters of target genes and recruits co-activators and histone acetyltransferases, facilitating transcription. Phosphorylation of the non-SMAD4 subunit(s) enables binding of SMAD4 to form heteromeric complexes that enter the nucleus to initiate gene transcription. DNA-binding specificity is conferred by other transcription factors binding to SMAD complexes. Interactions with coactivators or corepressors modulate their transcriptional activity. Can be heterotrimeric or heterodimeric. RNA polymerase II transcription regulator complex